Laboratory autoclaves



Sept. 29, 1964 E. F. MATTI-:SON

LABORATORY AUTocLAvEs 2 sheets-sheet 1 Filed Dec. 5, 1950 'INI/ENTOR.

EMoRY F, MATTEsoN ATTORNEY Sept. 29, 1964 E. F. MATTEsoN LABoRAToRYAuTocLAvEs 2 Sheets-Sheet 2 Filed Deo. 5. 1960 .w ma mw VA M w.. F Vl R O M .E

ATTORW United States Patent O 3,ltl,935 LBGRATRY U'QCLAVES Emory F. Matteson, Maniaroueclr, NY., assigner to hampaine industries, Inc., Louis, Mo., a corporation et Missouri Filed lec. 5, ldil, Ser. No. 73,337 3 Claims. (Cl. 23-29tl) This invention relates in general to laboratory autoclaves and, more particularly, to devices which are capable of carrying out iuspissation.

In certain procedures in biological laboratories, hospitals, and the like, it is necessary to pasteurize heat c0- agulabie liquids, such as bacteriological slants, and heatsensitive alkaloids, proteins, vaccines and serums. These operations are usually referred to as inspissation and it is an essential requirement to maintain constant temperature and humidity within a closed sterile chamber for various periods of time and in temperature ranges which are substantially below 212 F. Moreover, it is also essential that a partial pressure system be maintained in the chamber so that the steam, which is employed to maintain the desired temperature, will not condense and dilute the liquid being processed nor create a condition within the chamber such that the liquid being processed will tend to evaporate and become concentrated. Finally, it is necessary to create the desired temperature in the chamber without stratification or striation of the atmosphere within the chamber.

lt is, therefore, the primary object of the present invention to provide an autoclave having a chamber in which it is possible to maintain precisely controlled humidity, temperature and pressure relationships at tem perature ranges substantially below 2l2 F.

lt is another object of the present invention to provide an autoclave or inspissatory sterilizer of the type above defined which is highly efficient in the performance of its stated functions and can be fabricated economically.

It is a further object of the present invention to provide an autoclave of the type stated which may optionally be used as a conventional high-temperature sterilizer whenever desired without any mechanical or electrical modications.

It is also an object of the presen-t invention to provide an autoclave of the type stated which makes very economical use of Water, steam and electrical power.

With the above and other objects in view, my invention resides in the novel features of form, construction, arrangement and combination of parts presently described and pointed out in the claims.

l'n the accompanying drawings (two sheets)- j FIG. l is a longitudinal sectional view of an autoclave constructed in accordance with and embodying the present invention, shownig schematically the steam, water and electrical connections employed;

FIG. 2 is a schematic wiring diagram of the control circuit utilized in connection with the autoclave shown in FlG. l;

FlG. 3 is a longitudinal sectional view of a modied form of autoclave constructed in accordance With and embodying the present invention; and

FIG. 4 is a schematic wiring diagram of the control circuit utilized in connection with the modified form of autoclave shown in FlG. 3.

Referring now in more detail and by reference characters to the drawings, which illustrate practical embodiments of the present invention, A designates an autoclave comprising a preferably cylindrical chamber 1 enclosed within a jacket 2 and having its forward end closed by a suitably hinged and gasketed door 3. inasmuch as the chamber l, the jacket 2, and door 3 are conventional, these elements are not described or shown in detail herein.

Patented Sept. Z9, 194

Rigidly mounted in outwardly spaced relation to the rear wall 4 of the chamber 2l is a bafe plate 5 which is also marginally spaced around its periphery from the side walls 6 of the chamber l. Entering into the chamber l, preferably centrally of the back wall d, is a steamline '7, which is connected to the outlet end of a condenser tube disposed within a heat-exchange shell 9. The inlet end of the condenser tube S is connected to a steam-line 1li, which is, in turn, connected through a solenoid valve lll, a regulator valve l2, and a hand-operable shut-olf valve l?) to a source of high temperature live steam (the latter not being shown).

Also provided for use with the autoclave A is a water line E4 connected through a solenoid valve 15, a regulator valve lo, and a hand-operated shut-olf valve 17 to a source of water under pressure (the latter not being shown). Conventionally set into the water line 14 is a pipe 1S which connects .to a water-supply line 19, running to the heat-exchange shell 9, the latter being connected again to the remote side of the water line 14 by a return line 2;@ which extends through a regulator valve 2. and pipe T 22. Beyond the T 22, the water line 14 runs through a regulator valve Z3 and into a water-operated ejector or so-called aspirator 2f; conventionally provided with an internal constriction 2S and side arm duct Z6, which is, in turn, connected by means of a line 27 to a check valve 2S, and thence through a line Z9 to a manually adjustable thermostat 3u, the latter being connected by a line 3l to the lower forward portion of the chamber l. The ejector or aspirator 24 discharges downwardly through a tube 32 into an antivsiphoning fitting 33 which is connected through a conventional trap 34 to a sewer or waste-discharge line (the latter not being shown). Conventionally mounted in the heat-exchange shell 9 is a thermometer T1 for the usual purpose of affording temperature readings as the water in and flowing through the heat-exchange shell 9. Similarly inserted in the line 3l is a thermometer T2 for aiording a reading of the temperature in the chamber Il. The manually adjustable thermostat 3d is electrically connected .to the solenoid valves 1l, l5, and to a source of electrical power, as shown in FIG. 3.

it will, of course, be understood that, although the chamber l is shown and described herein as being cylindrical in shape, the present invention is not limited to any particular shape so far as the chamber l is concerned.

In use, the steam and water are turned on by suitable manipulation of the hand shut-oli` valves i3, 17, and the autoclave allowed to come up to temperature. Thereupon, the door 3 is opened to permit placement of bacteriological material within the chamber l.. The door 3 is then closed and the valves lll and 15 turned on. The aspirator 24 produces a moderate amount of suction on chamber l. Meanwhile, the steam lows through the condenser tube 8, warming the water to approximately F. and, in turn, issuing forth from the condenser tube 8 at a temperature of approximately 205 F. to 212 F., at which temperature it enters the chamber l, expands and is dilused by the baffle plate 5.

During operation, the thermostat 3@ operates intermittently, calling for water and steam simultaneously. Depending upon the selected setting, it has been found possible to maintain any desired temperature registered on the thermometer T2 in the range of 160 F. to 212 F. within an accuracy of plus or minus 2 F. for whatever length of time may be required. The constant flow of water through the ejector' 24 maintains the necessary degree of suction upon the chamber l so as to create the necessary partial-pressure condition therein. In order to maintain any selected temperature and partial-pressure relationship within the chamber l in the aforementioned range of from F. to 212 F., it is only necessary t0 adjust the thermostat switch 3d, which, in turn, energizes and de-energizes the steam and water supply valves and controls their cyclic operation as demanded by the sensing element of the thermostat. The constant suction from the ejector 24 alsoV creates circulation within the chamber 1 and stratiiication of steam is prevented. It will be noted thatV the thermostat 39 is merely in heat-exchange relationship to the llo'w between lines 3l and 29 so as to sense the outflow temperature at the discharge line 31 and thereby relates temperature control to partial-pressure.

For installation where a source of live steam is not conveniently available, it is possible to provide a modified form of autoclave B, as shown in FIG. 3, comprising a chamber 35 having a jacket 36 and a door 37 similar in all respects to the comparable elements of the autoclave A. structurally supported in any suitable manner beneath the chamber 35 and jacket 36 is a steam generator 3S including a chamber 39 having a water supply line til controlled by a conventional float valve j" so as to provide a body of water w within the chamber 39. Also mounted in the chamber 39 so as to be immersed in the body of water w is an electric heating element 4l which is of conventional type and is connected by electric wires in series with a thermostat 42 to a suitable source of elecrical power (not shown). The chamber 39 is also provided with a conventional thermometer i3 to afford a visual reading as yto the water temperature within the chamber 39.

Extending vertically up from the top of the chamber 39 is a pair of steam ducts 44, 45, opening into the jacket 36, and the latter is, in turn, connected from a point forwardly near the door 37 and at its top by a steam transfer line 46 to the center of the rear wall 47 of the chamber 39 so that steam will enter the chamber 39 and be diffused by a baille-plate 4S, which `is rigidly mounted across the back portion or the chamber 39 and functions in the same manner as the previously described baffle-plate 5. Interposed in the steam transfer line 46 is a solenoid valve 49 which serves the same function as the previously described solenoid valve 11.

Provided for co-operation with the autoclave B in a water line Si) which passes through a hand shut-off valve 51, a pressure regulator 52, a solenoid valve 53, a regulator valve 54, to an ejector or aspirator 55, and thence discharges into an anti-siphoning waste connection Se. The ejector has a side arm 57 which is connected by a suction line 58 to a check valve 59 and the latter is, in turn, connected by a suction line dit to a iitting 6l having a side-tube connection 62 which communicates to the interior of the chamber 39 at the forward lower end thereof and is provided with a thermometer 64. Mounted in the fitting 61 is a manually adjustable thermostat 63, the latter being electrically connected to the solenoid valves 49, 53, as shown. The foregoing elements are substantially identical in structure and function to the comparable elements previously described in connection with the autoclave A.

When in use, steam is generated in chamber 39, and maintained at a temperature of approximately 205 F. by action of the thermostat 42 energizing or de-energizing heat supply to the generator, and passes up through, and around, the jacket 36. Thence it flows through the steam transfer line 46 under control of the solenoid valve 49 and thermostat 63 to the interior of the chamber 39. As was described in connection with the autoclave A, the thermostat 63 will simultaneously call for water and steam intermittently and thereby maintain the same closely controlled conditions within the chamber 39 of the autoclave B as is true of the previously described autoclave A.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of Ithe laboratory autoclaves may be made and substituted for those herein shown and described without departing from the nature and principle of my invention. Y

Having thus described my invention, what l claim and desire to secure by Letters Patent is:

1. An autoclave comprising a chamber charged with steam having a temperature below the temperature corresponding to atmospheric pressure on the steam-table, a steam condensate discharge line connected to said chamber, a jet aspirator connected to said steam condensate discharge line for imposing suction upon the chamber and to maintain the chamber `at a pressure less than atmospheric pressure, a steam line discharging into the chamber, a baille directing the steam so as to produce uni# form circulation throughout the chamber, a water line connected to said jet aspirator, a condenser for conditioning the steam prior to entry into the chamber, said water line also being connected to said condenser, a thermostat responsive to the chamber temperature, solenoid valves interposed in said steam line and water line and being operatively connected to said thermostat for regulating the amount of flow in each of said steam and water lines, and an on-o valve in the steam line controlled by the thermostat.

2. An autoclave comprising a chamber, a steam line connecting said chamber withra source of steam, condenser means in heat exchange relationship with said steam line, a water line for delivering water to said condenser to reduce the temperature of said steam below 212 F., diffuser means in said chamber for spraying the steam mixture therein, a jet aspirator connected to said water line and to said chamber to reduce the pressure within said chamber below atmospheric pressure to prevent condensation of steam therein at a predetermined temperature below 212 F., a thermostat responsive to the chamber temperature, and valves in the steam line and the water line controlled by the thermostat.

3. An autoclave comprising a chamber adapted to be charged with steam having a temperature below the temperature corresponding to atmospheric pressure on the steam table, a steam line adapted to connect said charnber with a source of steam, a condenser located externally of said chamber and in heat exchange relationship with said steam line for reducing the temperature of steam below 212 F. prior to entry into the chamber, a baille in said chamber for directing the steam therein, a water line connecting said condenser with a source of water, a jet aspirator connected to said water line and operated by the water flowing therethrough, means connecting said jet aspirator to said chamber at a position remote from said baffle, said jet aspirator imposing a suction on said chamber sucient to create a vacuum within said chamber, a thermostat responsive to the chamber temperature solenoid valves interposed in said steam line and said water line and being operatively connected to said thermostat for regulating the amount of flow in each of said steam line and water line, and an off-on valve in the steam line controlled by the thermostat.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN AUTOCLAVE COMPRISING A CHAMBER CHARGED WITH STEAM HAVING A TEMPERATURE BELOW THE TEMPERATURE CORRESPONDING TO ATMOSPHERIC PRESSURE ON THE STEAM-TABLE, A STEAM CONDENSATE DISCHARGE LINE CONNECTED TO SAID CHAMBER, A JET ASPIRATOR CONNECTED TO SAID STEAM CONDENSATE DISCHARGE LINE FOR IMPOSING SUCTION UPON THE CHAMBER AND TO MAINTAIN THE CHAMBER AT A PRESSURE LESS THAN ATMOSPHERIC PRESSURE, A STEAM LINE DISCHARGING INTO THE CHAMBER, A BAFFLE DIRECTING THE SEAM SO AS TO PRODUCE UNIFORM CIRCULATION THROUGHOUT THE CHAMBER, A WATER LINE CONNECTED TO SAID JET ASPIRATOR, A CONDENSER FOR CONDITION ING THE STEAM PRIOR TO ENTRY INTO THE CHAMBER, SAID WATER LINE ALSO BEING CONNECTED TO SAID CONDENSER, A THERMOSTAT RESPONSIVE TO THE CHAMBER TEMPERATURE, SOLENOID VALVES INTERPOSED IN SAID STEAM LINE AND WATER LINE AND BEING OPERATIVELY CONNECTED TO SAID THERMOSTAT FOR REGULATING THE AMOUNT OF FLOW IN EACH OF SAID STEAM AND WATER LINES, AND AN ON-OFF VALVE IN THE STEAM LINE CONTROLLED BY THE THERMOSTAT. 